Identification and Characterization of SWEET Gene Family in Peanuts and the Role of AhSWEET50 in Sugar Accumulation

The SWEET (sugars will eventually be exported transporter) gene family represents a novel class of sugar transporters capable of bidirectionally transporting sugars along the concentration gradient. In this study, we identified 50 SWEET genes from the peanut cultivar Shitouqi, which were phylogenetically classified into four clades. Promoter analysis revealed that the AhSWEET genes contain multiple cis-acting elements associated with stress responses, growth regulation, and hormone signaling, suggesting their potential roles in plant development and adaptation to environmental challenges. Transcriptome profiling highlighted AhSWEET50 as the most highly expressed member during early seed development stages in both low- and high-sucrose peanut cultivars and also highly expressed at the mature stage. Subcellular localization confirmed the presence of AhSWEET50 in both the plasma membrane and cytoplasm, with predominant expression observed in embryos. The heterologous overexpression of AhSWEET50 in Arabidopsis significantly increased soluble sugar accumulation when compared to wild-type plants. These results validate the functional role of AhSWEET50 in sugar transport and provide a foundation for understanding the mechanisms of sugar allocation in peanuts, which has implications for improving seed quality through metabolic engineering.